A variety of methods are used for patterning composite sheet or multi-layer materials, for example ink-on-paper, metal-on-plastic, or more generally, one or more materials to be patterned on a substrate material. Conventional patterning methods include subtractive processes that start with the composite structure and remove one or more portions of undesired material from a substrate, such as patterning and etching, laser etching or cutting, mechanical abrasion or the like, and additive processes that add the desired material to a substrate, such as printing (for example ink jet, gravure, flexographic, or other types of printing), plating, vapor phase deposition, and the like.
Many of these methods are not amenable to cost-effective fast turn-around processing because of the time and cost associated with the patterning process. For example, roll-to-roll processing using a gravure roller to form a resist on a composite structure and then etching off the desirable material and cleaning the final product is an efficient way to make very large quantities of a single design, using a single material. Such roll-to-roll processes can be cost-effective despite the relatively long time, high complexity, and high cost associated with making the gravure roller and starting up the process, since such costs can be amortized over the very large volumes. At the other end of the process spectrum, digital printers, for example ink jet or wax or other printers, can relatively very quickly adapt to new patterns, but these techniques are relatively slow to produce large patterned areas, thus increasing the cost significantly beyond that of relatively more high-volume processes. In addition, such digital printers typically do not have sufficient throughput to match the capacity of subsequent processes that rely on their output, e.g., the manufacture of flexible printed circuit boards. Finally, additive processes, particularly for addition of electrically conductive materials (e.g., for printed circuit boards), typically have significantly lower conductivity than bulk conductive materials, for two reasons. The first is that the conductivity of the printed materials, for example printable conductive inks, is not typically as high as the bulk metal. For example, the printed materials may typically have about 3 times to about 6 times lower conductivity. The second is that these printed materials often cannot be printed at the same thickness as the bulk material. For example, they may have a thickness about 5 times to about 50 times thinner than available bulk materials.
Finally, many of these conventional processes use relatively large amounts of energy as well as relatively hazardous and/or toxic chemicals and may produce significant waste. For example, systems for patterning copper or metal layers on a substrate require large chemical etch baths that may have high operational, maintenance and disposal costs associated with large amounts of potentially non-environmentally friendly chemicals and other waste.
Accordingly, there is a need for solutions that provide for low-cost, environmentally friendly, high-throughput, easily changeable patterning of layered structures of any length, particularly for roll-to-roll processing.